Behavior of an Up-flow Anaerobic Sludge Bed (UASB) reactor at extreme salinity

Abstract

High salinity is one of the most well known inhibitors and salt concentrations above 1% are reported as highly saline. Salt may be found in the main collectors of municipal sewer systems which carry the risk of seawater infiltration and where domestic wastewaters are treated with landfill leachates such cases in Istanbul. Discharging of leachates into sewerage would also result in additional ammonium loads in Municipal Treatment Plants (MTPs). In this study, synthetic wastewater was fed to a lab-scale Upflow Anaerobic Sludge Bed (UASB) reactor operated at a constant hydraulic retention time (HRT) of 1 day. The salt concentration was increased artificially whereas the ammonium concentration was fixed at 1000 mg/l throughout the study. Results indicated no significant inhibition up to 2% salinity + 1000 mg/l NH4 and TOC removals could reach up to 88%. Besides, effective total biogas productions having methane content of 84% could be achieved. It is obvious that anaerobic microorganisms (especially methanogens) could well adapt to high salinity ratios. No inhibition at high ammonium concentration might have been attributed to the fact that the pH in the system was not high enough for the formation of free ammonia. Investigation of the combined effect of high salinity and ammonium was carried on by increasing the salinity to 3% in the study. Results indicated that TOC removals decreased to around 56% and 3% salinity caused . a sharp decrease both in organic material removal and total biogas production. Thus the critical salinity level was determined as 3% for the methanogens in the mesophilic anaerobic digesters.

Co-Digestion of Palm Oil Mill Effluent and Refined Glycerin Wash Water for Chemical Oxygen Demand Removal and Methane Production

“…The fact that the COD removal efficiency was not affected by the increasing concentration of NaCl in the digester suggests the feasibility of POME treatment despite high level of NaCl recorded. This is consistent with the previous study on high removal efficiency in the high salinity environment on COD [7] and ammonia nitrogen [10] . In the case of anaerobic salt bacteria, Halanaaerobium lacusrosei better performance was observed [5] .…”

“…In a Specific Methanogenic Activity (SMA) study, researchers found that at 25°C, high NaCl content of 30 g L −1 and above, the bacteria could not be acclimatized even in 50 days which may be due to osmotic stress which inhibited the reaction pathways of the degradation process [9] . This is supported with another study which found the critical salinity level was 3% for the methanogens in the mesophilic anaerobic digesters [7] . On the contrary, in a modern Submerge Anaerobic Membrane Reactor (SAMBR), researchers found the biomass could rapidly acclimatize to salinity of up to 40 g L −1 with 40-60% of Dissolved Organic Carbon (DOC) removal and satisfactory methane production rate [11] .…”

“…In many studies, the treatment technology for high salt or saline effluent has been studied for COD removal in laboratory scale digesters and pilot scale digesters [3][4][5][6][7][8][9][10][11][12] . Sodium ions (Na + ) appears to be essential for methanogenic bacteria due to its roles in a chemiosmotic coupling mechanism and 230 mg Na + L −1 or 10 mM was suggested as the optimal concentration for acetolastic methanogens in waste treatment process [3] .…”

Use of magnesit as a magnesium source for ammonium removal from leachate

“…In the literature, it is speculated that high concentration of salt formed during struvite precipitation may inhibit microbial activity in a following biological treatment process and cause decrease in the COD removal efficiency [18][19][20]. Following experiments were conducted for the investigation of effect of struvite pretreatment on the anaerobic treatment of leachate.…”

Performance and granulation in an upflow anaerobic sludge blanket (UASB) reactor treating saline sulfate wastewater

“…However, high salinity could cause osmotic stress on the bacterial cells and inhibition of reaction pathways in substrate degradation processes (Pollice et al 2000). High salinity was known to significantly reduce the treatment efficiency of anaerobic processes in mesophilic UASB reactors (Vallero et al 2004;Gomec et al 2005) and thermophilic UASB reactors (Vallero et al 2002). Vyrides et al highlighted the positive effect of the membrane in preventing the presence of high molecular weight organics in the effluent while also retaining biomass inside the reactor so that they could rapidly acclimatize to salinity (Vyrides and Stuckey 2009).…”